There was a guy I met once who had literally a 5 minute skit worked out to try to convince people to give him money. He would be standing in a parking lot pretending to be talking on a pay phone to his mother about how his nearby car had run out of gas. As someone walked by, he would loudly tell his "mom" to hold on a second and approach the person walking by, placing special emphasis on the word "mom" to be sure that other people could hear it.
I didn't give him any money, but I've wondered a lot about the guy since. He could have just been a run of the mill con artist I suppose, since I don't remember his clothes really indicating that he was definitely homeless. The thing that keeps bugging me about him, is that I'm positive they aren't enough people in the area he was doing this for him to make more than $5 an hour. His skit, while obviously fake, was really presented with a lot of energy and effort. If he was willing to put as much effort into flipping burgers as he did into this skit he would make substantially more money. So I keep wondering if there is something psychological about him that makes him think he is coming out more ahead by cheating people out of their money than by making it at a job.
I could be completely off base about him, and it could be that he makes more money doing that than I think. However, I worry that giving to someone not providing a service might in some people reinforce the mentality that you are earning more money if someone just gives it to you, even though in aggregate you are earning less than minimum wage. That's why I love buying papers from streetvibes sellers. I know I'm only reinforcing positive behavior.